Organic light emitting diode display device

ABSTRACT

An organic light emitting diode display device includes: an overcoating layer on a substrate having an emitting area and a non-emitting area and including a plurality of convex portions and a plurality of concave portions; a first electrode on the overcoating layer; a light emitting layer on the first electrode and including a first emitting material layer; and a second electrode on the light emitting layer, wherein the light emitting layer includes first, second and third emitting material layers sequentially under the second electrode, and wherein the first emitting material layer emits a first light of a first wavelength, the second emitting material layer emits the first light of the first wavelength, and the third emitting material layer emits a second light of a second wavelength different from the first wavelength.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the priority benefit of Korean PatentApplication No. 10-2018-0095139 filed in Republic of Korea on Aug. 14,2018, the disclosure of which is hereby incorporated by reference in itsentirety for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an organic light emitting diode displaydevice, and more particularly, to an organic light emitting diodedisplay device where a light extraction efficiency is improved.

Discussion of the Related Art

Recently, with the advent of an information-oriented society, asinterest in information displays for processing and displaying a massiveamount of information and demand for portable information media haveincreased, a display field has rapidly advanced. Thus, various light andthin flat panel display devices have been developed and highlighted.

Among the various flat panel display devices, an organic light emittingdiode (OLED) display device is an emissive type device and does notrequire a backlight unit used in a non-emissive type device such as aliquid crystal display (LCD) device. As a result, the OLED displaydevice has a light weight and a thin profile.

In addition, the OLED display device has advantages of a viewing angle,a contrast ratio, and power consumption as compared with the LCD device.Furthermore, the OLED display device can be driven with a low directcurrent (DC) voltage and has rapid response speed. Moreover, since innerelements of the OLED display device have a solid phase, the OLED displaydevice has high durability against an external impact and has a wideavailable temperature range.

In the OLED display device, while light emitted from a light emittinglayer passes through various components and is emitted to an exterior, alarge amount of the light is lost. As a result, the light emitted to theexterior of the OLED display device is only 20% of the light emittedfrom the light emitting layer.

Here, since the amount of the light emitted from the light emittinglayer is increased along with the amount of a current applied to theOLED display device, it is possible to further increase luminance of theOLED display device by applying more currents to the light emittinglayer. However, in this case, power consumption is increased, andlifetime of the OLED display device is also reduced.

Therefore, to improve a light extraction efficiency of the OLED displaydevice, an OLED display device where a microlens array (MLA) is attachedto an outer surface of a substrate or a microlens is formed in anovercoating layer has been suggested.

However, even when the microlens array is attached to the outer surfaceof the OLED display device or the microlens is formed in the OLEDdisplay device, a large amount of light is confined in the OLED displaydevice and only a small amount of light is extracted to an exterior.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an organic lightemitting diode display device that substantially obviates one or more ofthe problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide an organic lightemitting diode display device where a light extraction efficiency isimproved and a lifetime is extended.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, anorganic light emitting diode display device includes: a substrate; anovercoating layer on the substrate and including a plurality of convexportions and a plurality of concave portions; a first electrode on theovercoating layer; a light emitting layer on the first electrode; and asecond electrode on the light emitting layer, wherein the light emittinglayer includes first, second and third emitting material layerssequentially under the second electrode, and wherein the first emittingmaterial layer emits a first light of a first wavelength, the secondemitting material layer emits the first light of the first wavelength,and the third emitting material layer emits a second light of a secondwavelength different from the first wavelength.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a cross-sectional view showing an organic light emitting diodedisplay device according to a first embodiment of the presentdisclosure;

FIG. 2 is a magnified view of A of FIG. 1;

FIG. 3 is a contour map showing a light of an organic light emittingdiode display device according to a comparison example;

FIG. 4 is a cross-sectional view showing a light emitting diode of anorganic light emitting diode display device according to a secondembodiment of the present disclosure; and

FIG. 5 is a graph showing an external quantum efficiency of a bluecolored light of an organic light emitting diode display deviceaccording to a second embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present disclosure, examplesof which are illustrated in the accompanying drawings.

FIG. 1 is a cross-sectional view showing an organic light emitting diodedisplay device according to a first embodiment of the presentdisclosure. All the components of the organic light emitting diodedisplay devices according to all embodiments of the present disclosureare operatively coupled and configured.

In FIG. 1, an organic light emitting diode (OLED) display device 100 canhave a top emission type or a bottom emission type according to anemission direction of a light. A bottom emission type OLED displaydevice can be exemplarily illustrated hereinafter. All of elements ofthe organic light emitting diode (OLED) display device 100 areoperatively coupled and configured.

The OLED display device 100 includes a substrate having a driving thinfilm transistor (TFT) DTr and a light emitting diode E thereon and aprotecting film 102 encapsulating the substrate 101.

The substrate 101 includes a plurality of pixel regions P and each pixelregion P includes an emitting area EA where the light emitting diode Eis disposed and an image is substantially displayed and a non-emittingarea NEA along an edge of the emitting area EA. The non-emitting areaNEA includes a switching area TrA where the driving TFT DTr is disposed.

A semiconductor layer 103 is disposed in the switching area TrA of thenon-emitting area NEA of the pixel region P on the substrate 101. Thesemiconductor layer 103 can include silicon and can have an activeregion 103 a in a central portion and source and drain regions 103 b and103 c in both side portions of the active region 103 a. The activeregion 103 a can function as a channel of the driving TFT DTr, and thesource and drain regions 103 b and 103 c can be doped with impurities ofa relatively high concentration.

A gate insulating layer 105 is disposed on the semiconductor layer 103.

A gate electrode 107 and a gate line (not shown) are disposed on thegate insulating layer 105. The gate electrode 107 corresponds to theactive region 103 a of the semiconductor layer 103, and the gate line isconnected to the gate electrode 107 to extend along one direction.

A first interlayer insulating layer 109 a is disposed on the gateelectrode 107 and the gate line. The first insulating layer 109 a andthe gate insulating layer 105 has first and second semiconductor contactholes 116 exposing the source and drain regions 103 b and 103 c in bothside portions of the active region 103 a.

Source and drain electrodes 110 a and 110 b spaced apart from each otherare disposed on the first interlayer insulating layer 109 a having thefirst and second semiconductor contact holes 116. The source electrode110 a is connected to the source region 103 b through the firstsemiconductor contact hole 116, and the drain electrode 110 b isconnected to the drain region 103 c through the second semiconductorcontact hole 116.

A second interlayer insulating layer 109 b is disposed on the source anddrain electrodes 110 a and 110 b and the first interlayer insulatinglayer 109 a exposed between the source and drain electrodes 110 a and110 b.

The source and drain electrodes 110 a and 110 b, the semiconductor layer103 including the source and drain regions 103 b and 103 c contactingthe source and drain electrodes 110 a and 110 b, respectively, the gateinsulating layer 105 and the gate electrode 107 constitute the drivingTFT DTr.

Although not shown, a data line can be disposed on the second interlayerinsulating layer 109 b. The data line can cross the gate line to defineeach pixel region P. A switching TFT having the same structure as thedriving TFT DTr can be connected to the driving TFT DTr.

The switching TFT and the driving TFT DTr can exemplarily have one of anamorphous silicon (a-Si) TFT, a polycrystalline silicon (p-Si) TFT, asingle crystal silicon (c-Si) TFT and an oxide TFT according to thesemiconductor layer 103. Although the switching TFT and the driving TFTDTr in the first embodiment of FIG. 1 have a top gate type where thesemiconductor layer 103 includes polycrystalline silicon or an oxidesemiconductor material, the switching TFT and the driving TFT DTr canhave a bottom gate type where the semiconductor layer 103 includesintrinsic amorphous silicon and impurity-doped amorphous silicon inanother embodiment.

When the semiconductor layer 103 includes the oxide semiconductormaterial, a light shielding layer (not shown) can be disposed under thesemiconductor layer 103 of the oxide semiconductor material, and abuffer layer (not shown) can be disposed between the light shieldinglayer and the semiconductor layer 103.

A wavelength converting layer 106 is disposed on the second interlayerinsulating layer 109 b corresponding to the emitting area EA of eachpixel region P.

The wavelength converting layer 106 can include a color filtertransmitting only a light having a wavelength of a predetermined colorcorresponding to each pixel region P among a white light emitted fromthe light emitting diode E to the substrate 101.

The wavelength converting layer 106 can transmit only a light having awavelength corresponding to a red color, a green color or a blue color.For example, in the OLED display device 100, a single unit pixel regioncan include red, green and blue pixel regions P, and the wavelengthconverting layer 106 in the red, green and blue pixel regions P caninclude red, green and blue color filters, respectively.

In the OLED display device 100, the single unit pixel region can furtherinclude a white pixel region where the wavelength converting layer 106is not disposed.

In another embodiment, the wavelength converting layer 106 can include aquantum dot which have a size capable of emitting a light of apredetermined color corresponding to each pixel region P according to awhite light emitted from the light emitting diode E to the substrate101. Here, the quantum dot can include at least one selected from agroup including CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe,CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS,CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS,CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe,HgZnSTe, GaN, GaP, GaAs, AlN, AlP, AlAs, InN, InP, InAs, GaNP, GaNAs,GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs,GaInNP. GaInNAs, GaInPAs, InAlNP, InAlNAs, InAlPAs and SbTe. However, amaterial of the quantum dot is not limited thereto.

For example, the wavelength converting layer 106 in the red pixel regioncan include a quantum dot of CdSe or InP, the wavelength convertinglayer 106 in the green pixel region can include a quantum dot ofCdZnSeS, and the wavelength converting layer 106 in the blue pixelregion can include a quantum dot of ZnSe. The OLED display device 100where the wavelength converting layer 106 includes a quantum dot canhave a relatively high color reproducibility.

In another embodiment, the wavelength converting layer 106 can include acolor filter containing a quantum dot.

An overcoat layer 108 which has a first drain contact hole 108 aexposing the drain electrode 110 b with the second interlayer insulatinglayer 109 b is disposed on the wavelength converting layer 106. Theovercoating layer 108 has a plurality of concave portions 118 and aplurality of convex portions 117 on a top surface thereof. The pluralityof concave portions 118 and the plurality of convex portions 117 arealternately disposed with each other to constitute a microlens ML.

The overcoating layer 108 can include an insulating material having arefractive index of 1.5. For example, the overcoating layer 108 caninclude one of acrylic resin, epoxy resin, phenol resin, polyamideresin, polyimide resin, unsaturated polyester resin, polyphenyleneresin, polyphenylenesulfide resin, benzocyclobutene and photoresist.However, a material of the overcoating layer 108 is not limited thereto.

The plurality of convex portions 117 can have a structure to define orsurround the plurality of concave portions 118, respectively, and canhave a bottom surface portion 117 a, a top surface portion 117 b and aside surface portion 117 c.

The side surface portion 117 c can be an entire or a whole of a slantedsurface constituting the top surface portion 117 b. A slope of the sidesurface portion 117 c can increase from the bottom surface portion 117 ato the top surface portion 117 b such that the side surface portion 117c can have a maximum slope Smax at a portion adjacent to the top surfaceportion 117 b.

Since a path of a light emitted from the light emitting layer 113 ischanged toward the substrate 101 by the plurality of convex portions117, the light extraction efficiency of the OLED display device 100increases.

A first electrode 111 connected to the drain electrode 110 b of thedriving TFT DTr is disposed on the overcoating layer 108 constitutingthe microlens ML. For example, the first electrode 111 can be an anodeof the light emitting diode E and can include a material having arelatively high work function.

The first electrode 111 is disposed in each pixel region P, and a bank119 is disposed between the first electrodes 111 in the adjacent pixelregions P. The first electrode 111 is separated in each pixel region Pwith the bank 119 as a border between the adjacent pixel regions P.

The bank 119 includes an opening exposing the first electrode 111, andthe opening of the bank 119 is disposed to corresponds to the emittingarea EA. The plurality of convex portions 117 and the plurality ofconcave portions 118 constituting the microlens ML are disposed in anentire or a whole of the opening of the bank 119. For example, theplurality of convex portions 117 and the plurality of concave portions118 can contact an edge portion of the bank 119.

Further, the opening of the bank 119 is disposed to correspond to thewavelength converting layer 106. For example, the edge portion of thebank 119 can overlap an edge portion of the wavelength converting layer106. Since the wavelength converting layer 106 overlaps the bank 119, aleakage of a light not passing through the wavelength converting layer106 is prevented. In embodiments, the plurality of convex portions 117and the plurality of concave portions 118 can be located to correspondto the wavelength converting layer 106. The wavelength converting layer106 can be interposed between the substrate 101 and the overcoatinglayer 108. In embodiments, the plurality of convex portions 117 can bemore distal to the substrate 101 than the plurality of concave portions118.

A light emitting layer 113 is disposed on the first electrode 111. Thelight emitting layer 113 can have a single layer of an emittingmaterial. Alternatively, the light emitting layer 113 can have amultiple layer including a hole injecting layer, a hole transportinglayer, an emitting material layer, an electron transporting layer and anelectron injecting layer for increasing an emission efficiency.

The first electrode 111 and the light emitting layer 113 sequentially onthe overcoating layer 108 can have a shape according to a morphology ofthe plurality of convex portions 117 and the plurality of concaveportions 118 of the top surface of the overcoating layer 108 toconstitute the microlens ML.

The light emitting layer 113 can have different thicknesses in theconvex portion 117 and the concave portion 118 of the microlens ML.

The thickness of the light emitting layer 113 in a region correspondingto the side surface portion 117 c of the convex portion 117 of themicrolens ML can be smaller than the thickness of the light emittinglayer 113 in a region corresponding to the concave portion 118 of themicrolens ML. The thickness of the light emitting layer 113 can bedefined as a length perpendicular to a tangential line C1 and C2 (ofFIG. 2) of the top and bottom surfaces of the light emitting layer 113.

In the OLED display device 100, since the light emitting layer 113 hasdifferent thicknesses in the convex portion 117 and the concave portion118 constituting the microlens ML, a distance from the second electrode115 to the emitting material layers 203 a, 203 b and 203 c (of FIG. 3)of the light emitting layer 113 in the concave portion 118 of themicrolens ML is different from a distance from the second electrode 115to the emitting material layers 203 a, 203 b and 203 c of the lightemitting layer 113 in the side surface portion 117 c of the convexportion 117 of the microlens ML.

Accordingly, in the OLED display device 100, the emitting materiallayers 203 a, 203 b and 203 c are disposed at a predetermined locationin the light emitting layer 113 constituting the microlens ML.

Since the emitting material layers 203 a, 203 b and 203 c are disposedat specific positions in the light emitting layer 113 constituting themicrolens ML, the light extraction efficiency of the light emitted fromthe light emitting diode E increases.

A second electrode 115 is disposed on an entire or a whole of the lightemitting layer 113. For example, the second electrode 115 can be acathode.

The second electrode 115 can have a shape according to a morphology ofthe plurality of convex portions 117 and the plurality of concaveportions 118 of the top surface of the overcoating layer 108 toconstitute the microlens ML.

When a voltage is applied to the first and second electrodes 111 and 115according to a signal, a hole injected from the first electrode 111 andan electron injected from the second electrode 115 are transmitted tothe light emitting layer 113 to constitute an exciton. When the excitontransitions from an excited state to a ground state, a light can beemitted from the light emitting layer 113 as a visible ray.

The light of the light emitting layer 113 can pass through thetransparent first electrode 111 to be emitted toward an exterior suchthat an image is displayed.

Since the overcoating layer 108 constitutes the microlens ML, the lightconfined in the interior of the light emitting layer 113 due to a totalreflection can be transmitted with an angle smaller than a criticalangle of the total reflection by the microlens ML of the overcoatinglayer 108 to be extracted to the exterior by a multiple reflection. As aresult, the light extraction efficiency of the OLED lighting apparatus100 is improved.

In addition, since the microlens ML of the overcoating layer 108, thefirst electrode 111, the light emitting layer 113 and the secondelectrode 115 is disposed in an entire or a whole of the opening of thebank 119 corresponding to the emitting area EA, the entire or the wholeof the emitting area EA is used for the microlens ML and the lightextraction efficiency is maximized.

A protecting film 102 of a thin film type is disposed on the driving TFTDTr and the light emitting diode E, and a face seal 104 is disposedbetween the light emitting diode E and the protecting film 102. The faceseal 104 can include an organic material or an inorganic material whichis transparent and has an adhesive property. The protecting film 102 andthe substrate 101 can be attached to each other by the face seal 104 toencapsulate the OLED display device 100.

To prevent penetration of an external oxygen and a moisture into aninterior of the OLED display device 100, the protecting film 102 caninclude at least two inorganic protecting films. An organic protectingfilm for supplementing impact resistance of the at least two inorganicprotecting films can be interposed between the at least two inorganicprotecting films.

In the structure where the organic protecting film and the inorganicprotecting film are alternately laminated with each other, the inorganicprotecting film can completely wrap the organic protecting film suchthat penetration of the moisture and the oxygen through a side surfaceof the organic protecting film is prevented.

As a result, penetration of the moisture and the oxygen from theexterior to the interior of the OLED display device 100 can beprevented.

In the OLED display device 100, a polarizing plate (not shown) forpreventing reduction of a contrast ratio due to an external light can bedisposed on an outer surface of the transparent substrate 101. Since thepolarizing plate blocking the external light is disposed on a surface ofthe OLED display device 100 in a driving mode where a light from thelight emitting layer 113 is emitted, the contrast ratio increases.

In the OLED display device 100, since the emitting material layers 203a, 203 b and 203 c are disposed at predetermined positions in the lightemitting layer 113 constituting the microlens ML due to the overcoatinglayer 108, the light extraction efficiency of the light emitted from thelight emitting diode E increases.

FIG. 2 is a magnified view of A of FIG. 1.

In FIG. 2, the first electrode 111, the light emitting layer 113 and thesecond electrode 115 are sequentially disposed on the overcoating layer108 having the microlens ML of the plurality of concave portions 118 andthe plurality of convex portions 117 alternating with each other. Thefirst electrode 111, the light emitting layer 113 and the secondelectrode 115 constitute the light emitting diode E.

The first electrode 111, the light emitting layer 113 and the secondelectrode 115 sequentially on the overcoating layer 108 have a shapeaccording to a morphology of the top surface of the overcoating layer108 to constitute the microlens ML.

Each convex portion 117 can have a bottom surface portion 117 a, a topsurface portion 117 b and a side surface portion 117 c. The side surfaceportion 117 c can be an entire or a whole of a slanted surfaceconstituting the top surface portion 117 c.

The side surface portion 117 c can be divided into a lower region LA, amiddle region MA and an upper region UA according to a total height Hbetween the bottom surface portion 117 a and the top surface portion 117b. The lower region LA can be defined as a region from the bottomsurface portion 117 a to a half of the total height H (H/2). The middleregion MA between the lower region LA and the upper region UA can bedefined as a region from the half of the total height H (H/2) to fourfifth of the total height H (4H/5). The upper region UA can be definedas a region from the four fifth of the total height H (4H/5) to the topsurface portion 117 b.

To further increase the light extraction efficiency of the lightemitting layer 113, the convex portion 117 of the overcoating layer 108can have a structure where the top surface portion 117 b has a sharpshape or a tip. For example, the convex portion 117 can have across-section of triangle shape including a vertex corresponding to thetop surface portion 17 b, a bottom side corresponding to the bottomsurface portion 117 a and a hypotenuse corresponding to the side surfaceportion 117 c.

An angle θ1 and θ2 of the side surface portion 117 c of the convexportion 117 of the overcoating layer 108 can gradually increase from thebottom surface portion 117 a to the top surface portion 117 b. The angleθ1 and θ2 is defined as an angle between the tangential line C1 and C2of the side surface portion 117 c and a horizontal surface (i.e., thebottom surface portion 117 a). The side surface portion 117 c can havethe maximum slope Smax when the angle θ1 and θ2 becomes the maximumvalue. The slope can be defined by a tangent value of the angle (tan θ).

Since the angle θ1 and θ2 of the side surface portion 117 c graduallyincreases from the bottom surface portion 117 a to the top surfaceportion 117 b, the side surface portion 117 c of the convex portion 117of the overcoating layer 108 has the maximum slope Smax in the upperregion UA adjacent to the top surface portion 117 b.

The first electrode 111, the light emitting layer 113 and the secondelectrode 115 on the overcoating layer 108 having the microlens ML ofthe concave portion 118 and the convex portion 117 have the microlens MLon the top surface thereof. The convex portion 117 can include thebottom surface portion 117 a, the tope surface portion 117 b and theside surface portion 117 c, and the side surface portion 117 c caninclude the upper region UA, the middle region MA and the lower regionLA.

In the OLED display device 100, since the light emitting layer 113 isdisposed on the overcoating layer 108 constituting the microlens ML, thelight emitting layer 113 can have different thicknesses d1, d2, d3 andd4 in different regions. The light emitting layer 113 can be formed tohave the different thicknesses d1, d2, d3 and d4 corresponding to theconcave portion 118 and the convex portion 117 of the microlens ML.

The thickness of the light emitting layer 113 can be defined as a lengthperpendicular to the tangential line C1 and C2 of the light emittinglayer 113. For example, the third and fourth thicknesses d3 and d4 ofthe light emitting layer 113 of the side surface portion 117 c of theconvex portion 117 of the microlens ML can be smaller than the first andsecond thicknesses d1 and d2 of the light emitting layer 113 of theconcave portion 118 and the top surface portion 117 b of the convexportion 117.

The thickness d3 and d4 of the light emitting layer 113 of the sidesurface portion 117 c of the convex portion 117 can gradually decreasefrom the lower region LA to the upper region UA.

Since the light emitting layer 113 is formed on the overcoating layer108 having the microlens ML, the side surface portion 117 c of theconvex portion 117 of the overcoating layer 108 can have the angle θ1and θ2 gradually increasing from the bottom surface 117 a to the topsurface portion 117 b. As a result, the third and fourth thicknesses d3and d4 of the light emitting layer 113 of the side surface portion 117 care smaller than the first and second thicknesses d1 and d2 of the lightemitting layer 113 of the concave portion 118 and the top surfaceportion 117 b.

Since the angle θ1 and θ2 of the side surface portion 117 c graduallyincreases from the lower region LA to the upper region UA, the lightemitting layer 113 of the side surface portion 117 c can have the fourththickness d4 as the minimum value in the upper region UA where the angleθ2 has a relatively great value and can have the third thickness d3 asthe maximum value in the middle region MA where the angle θ1 has arelatively small value.

For example, the first thickness d1 can be equal to or greater than thesecond thickness d2, the second thickness d2 can be greater than thethird thickness d3, and the third thickness d3 can be greater than thefourth thickness d4, e.g., d1≥d2>d3>d4.

In the light emitting diode E, the light emission occurs in a regionhaving a relatively high current density. Since the light emitting layer113 has a relatively small thickness d4 in the upper region UA of theconvex portion 117, the light emitting layer 113 can have a relativelyhigh current density and a relatively strong light emission in the upperregion UA of the convex portion 117. In addition, since the lightemitting layer 113 has a relatively great thickness d in the lowerregion LA of the convex portion 117, the light emitting layer 113 canhave a relatively low current density and a relatively weak lightemission in the lower region LA of the convex portion 117. As a result,the upper region UA of each of the plurality of convex portions 117where the relatively strong light emission occurs can be defined as aneffective emission region B. When the light emitting diode E is driven,an electric field is locally concentrated on the effective emissionregion B. As a result, a main current path is constituted and a mainemission occurs in the effective emission region B.

The light emitting layer 113 has the main emission in the effectiveemission region B having a relatively small thickness d4 as comparedwith the top surface portion 117 b of the convex portion 117 and theconcave portion 118. Since the emitting material layers 203 a, 203 b and203 c are disposed at predetermined positions in the light emittinglayer 113 based on the thickness of the light emitting layer 113 in theeffective emission region B, the light extraction efficiency of thelight emitted from the light emitting diode E increases.

When the positions of the emitting material layers 203 a, 203 b and 203c are determined in the light emitting layer 113 based on the effectiveemission region B of the light emitting layer 113 constituting themicrolens ML, the position of the emitting material layers 203 a, 203 band 203 c can be determined to satisfy a condition for a cavity peak ofan optical property.

The cavity peak can be defined as a maximum optical intensity. Forexample, a light generated between two mirrors can have the cavity peakat a position where the light has a maximum intensity due to aconstructive interference of the reflected lights.

The position of the cavity peak can be determined according to awavelength of the light. The position of the cavity peak in the firstelectrode 111, the light emitting layer 113 and the second electrode 115having a flat structure is different from the position of the cavitypeak in the first electrode 111, the light emitting layer 113 and thesecond electrode 115 constituting the microlens ML.

In the OLED display device 100, since the emitting material layers 203a, 203 b and 203 c are disposed at predetermined positions in the lightemitting layer 113 based on the cavity peak of the emitting materiallayers 203 a, 203 b and 203 c as well as the effective emission region Bof the light emitting layer 113, the light extraction efficiency furtherincreases.

As a result, the light efficiency and the lifetime of the OLED displaydevice 100 are further improved.

FIG. 3 is a contour map showing a light of an organic light emittingdiode display device according to a comparison example, FIG. 4 is across-sectional view showing a light emitting diode of an organic lightemitting diode display device according to a second embodiment of thepresent disclosure, and FIG. 5 is a graph showing an external quantumefficiency of a blue colored light of an organic light emitting diodedisplay device according to a second embodiment of the presentdisclosure.

In FIG. 3, a contour map shows an intensity of a light according to acolor (a wavelength) and a position as a contour line in an OLED displaydevice according to a comparison example where each of a firstelectrode, a light emitting layer and a second electrode has a flatshape. The x-axis represents a wavelength (color) of a light and they-axis represents a distance from the second electrode.

When emitting material layers emitting colored lights are disposed atpositions having a relative maximum intensity for correspondingwavelengths, the light efficiency increases.

The light emitting layer emits a white light by mixing a blue coloredlight having a wavelength of 440 nm to 480 nm and a yellow-green coloredlight having a wavelength of 510 nm to 590 nm. According to the contourmap, the blue colored light having a wavelength of 440 nm to 480 nm hascavity peaks at positions having distances of 250 Å, 1500 Å, 2700 Å and4000 Å from the second electrode. The cavity peaks can be defined asfirst, second, third and fourth blue cavity peaks B1, B2, B3 and B4.

The yellow-green colored light having a wavelength of 510 nm to 590 nmhas cavity peaks at positions having distances of 300 Å, 1800 Å and 3400Å from the second electrode. The cavity peaks can be defined as first,second and third yellow-green cavity peaks YG1, YG2 and YG3.

The light emitting layer can includes two blue emitting material layerseach emitting a blue colored light and one yellow-green emittingmaterial layer emitting a yellow-green colored light for increasing aluminance of the blue colored light. Since the blue colored light havinga relatively short wavelength has a relatively low emission efficiencydue to a material property, the emission efficiency of the blue coloredlight can be a half of the emission efficiency of the yellow-greencolored light. As a result, the uniform white colored light can begenerated from combination of the two blue emitting material layers andone yellow-green emitting material layer.

Accordingly, when each of first and second blue emitting material layersemitting the blue colored light is disposed to correspond to one of thefirst, second, third and fourth blue cavity peaks B1, B2, B3 and B4 anda yellow-green emitting material layer emitting the yellow-green lightis disposed to correspond to one of the first, second and thirdyellow-green peaks YG1, YG2 and YG3, the first and second blue emittingmaterial layers and the yellow-green emitting material layer of thelight emitting layer can have a maximum emission efficiency.

In addition, as the first and second blue emitting material layers andthe yellow-green emitting material layer are disposed closer to thesecond electrode, a total thickness of the light emitting diode isreduced and the emission efficiency further increases. For example,based on thicknesses of organic layers such as a hole transporting layerand an electron transporting layer between the emitting material layers,the first and second blue emitting material layers can be disposed tocorrespond to the first and third blue cavity peaks B1 and B3,respectively, and the yellow-green emitting material layer can bedisposed to correspond to the second yellow-green cavity peak YG2.

When the first blue emitting material layer is disposed to correspond tothe first blue cavity peak B1 and the yellow-green emitting materiallayer is disposed to correspond to the first yellow-green cavity peakYG1, it is difficult to dispose the organic layers between the firstblue emitting material layer and the yellow-green emitting materiallayer because the first blue emitting material layer and theyellow-green emitting material layer are separated by a short distance.

Further, when the first blue emitting material layer is disposed tocorrespond to the second blue cavity peak B2 and the yellow-greenemitting material layer is disposed to correspond to the secondyellow-green cavity peak YG2, it is difficult to dispose the organiclayers between the first blue emitting material layer and theyellow-green emitting material layer because the first blue emittingmaterial layer and the yellow-green emitting material layer areseparated by a short distance.

As a result, the first and second blue emitting material layers can bedisposed to correspond to the first and third blue cavity peaks B1 andB3, respectively, and the yellow-green emitting material layer can bedisposed to correspond to the second yellow-green cavity peak YG2.

Accordingly, in the OLED display device according to a comparisonexample where the first electrode, the light emitting layer and thesecond electrode have a flat shape, the maximum emission efficiency isobtained by disposing the first and second blue emitting material layersand the yellow-green emitting material layer to correspond to the cavitypeaks, i.e., disposing the first blue emitting material layer emitting ablue colored light to have a distance of 250 Å from the secondelectrode, disposing the second blue emitting material layer emitting ablue colored light to have a distance of 2700 Å from the secondelectrode and disposing the yellow-green emitting material layeremitting a yellow-green colored light to have a distance of 1800 Å fromthe second electrode.

In the OLED display device 100 (of FIG. 1) according to a firstembodiment of the present disclosure where the first electrode 111 (ofFIG. 1), the light emitting layer 113 (of FIG. 1) and the secondelectrode 115 (of FIG. 1) constitute a microlens ML (of FIG. 1) forimproving a light extraction efficiency, since the light emitting layer113 has a relatively small thickness in the effective emission region B(of FIG. 2), the first blue emitting material layer can have a distanceof 260 Å to 460 Å from the second electrode 115, the second blueemitting material layer can have a distance of 3500 Å from the secondelectrode 115 and the yellow-green emitting material layer can have adistance of 2500 Å from the second electrode 115 based on the contourmap for compensating the relatively small thickness of the lightemitting layer 113 in the effective emission region B.

As a result, in the OLED display device 110 according to a firstembodiment where the first electrode 111, the light emitting layer 113and the second electrode 115 constitute a microlens ML (of FIG. 1), thefirst blue emitting material layer, the yellow-green emitting materiallayer and the second blue emitting material layer of theblue/yellow-green/blue colored lights are sequentially disposed underthe second electrode 115.

In a light emitting diode E (of FIG. 1) of an organic light emittingdiode (OLED) display device 100 (of FIG. 1) according to a secondembodiment of the present disclosure, the maximum emission efficiency isobtained and a total thickness of the light emitting diode E is reducedby disposing first, second and third emitting material layers emittingblue, blue and yellow-green colored lights, respectively, sequentiallyunder a second electrode 115 (of FIG. 1) to satisfy cavity peaks. As aresult, the maximum emission efficiency is obtained and a totalthickness of the light emitting diode E is reduced.

In FIG. 4, a light emitting diode E includes first and second electrodes111 and 115 and a light emitting layer 113 between the first and secondelectrodes 111 and 115, and the light emitting layer 113 includes first,second and third emitting material layers (EMLs) 203 a, 203 b and 203 cand first and second auxiliary layers 208 and 209 among the first,second and third emitting material layers (EMLs) 203 a, 203 b and 203 c.

The first electrode 111 can be an anode supplying a hole and having arelatively great or large work function. For example, the firstelectrode 111 can include one of a metal oxide such as indium tin oxide(ITO) and indium zinc oxide (IZO), a mixture of a metal and an oxidesuch as zinc oxide and aluminum (ZnO:Al) and tin oxide and antimony(SnO₂:Sb) and a conductive polymer such as poly(3-methylthiophene),poly[3,4-(ethylene-1,2-dioxy)thiophene](PEDT), polypyrrole andpolyaniline. In addition, the first electrode 111 can include one ofcarbon nano tube (CNT), graphene and silver nano wire.

The second electrode 115 can be a cathode supplying an electron andhaving a relatively small work function. For example, the secondelectrode 115 can have a single layer of an alloy of a first metal(e.g., Ag) having a relatively small work function and a second metal(e.g., Mg), a double layer of the first and second metals, or a multiplelayer of the alloy of the first and second metals.

The second electrode 115 can be a reflective electrode and the firstelectrode 111 can be a transflective electrode. Alternatively, the firstelectrode 111 can be a reflective electrode and the second electrode 115can be a transparent electrode. For example, at least one of the firstand second electrodes 111 and 115 can be a reflective electrode.

The second electrode 115 can include a material having a reflectanceequal to or greater than 90% in a visible ray band, and the firstelectrode 111 can include a material having a transmittance equal to orgreater than 80% in the visible ray band. For example, the visible rayband can be a wavelength band of 380 nm to 800 nm.

When the second electrode 115 has a reflectance equal to or greater than90%, most of a light from the light emitting layer 113 to the secondelectrode 115 can be reflected by the second electrode 115 to proceedtoward the first electrode 111 in the light emitting diode E. Inaddition, when the first electrode 111 has a transmittance equal to orgreater than 80%, a large amount of the light can pass through the firstelectrode 111.

The second electrode 115 can have a thickness of 90 nm to 120 nm forincreasing a reflectance in the visible ray band. However, a thicknessof the second electrode 115 is not limited thereto and can varyaccording to a material of the second electrode 115. The first electrode111 can have a thickness of 115 nm to 135 nm for increasing atransmittance in the visible ray band. However, a thickness of the firstelectrode 111 is not limited thereto and can vary according to amaterial of the first electrode 111. In embodiments, a thickness of atleast one of the first electrode 111 and the second electrode 115corresponding to the plurality of convex portions 117 can be smallerthan a thickness of the at least one of the first electrode 111 and thesecond electrode 115 corresponding to the plurality of concave portions118.

A first electron transporting layer (ETL1) 205 is disposed between thesecond electrode 115 and the first emitting material layer 203 a, and afirst auxiliary layer 208 is disposed between the first emittingmaterial layer 203 a and the second emitting material layer 203 b. Asecond auxiliary layer 209 is disposed between the second emittingmaterial layer 203 b and the third emitting material layer 203 c, and afirst hole transporting layer (HTL1) 207 is disposed between the thirdemitting material layer 203 c and the first electrode 111.

An electron injecting layer (EIL) (not shown) can be disposed betweenthe second electrode 115 and the first electron transporting layer (ETL)205. The electron injecting layer can assist injection of the electronfrom the second electrode 115 to the first electron transporting layer(ETL1) 205.

The first electron transporting layer (ETL1) 205 can have at least twolayers or can include at least two materials. A hole blocking layer(HBL) (not shown) can be disposed between the first electrontransporting layer (ETL1) 205 and the first emitting material layer 203a. Since the hole blocking layer prevents transmission of a holeinjected into the first emitting material layer 203 a to the firstelectron transporting layer (ETL) 205, combination of a hole and anelectron is improved in the first emitting material layer 203 a and anemission efficiency of the first emitting material layer 203 a isimproved.

The first electron transporting layer (ETL1) 205 and the hole blockinglayer can be formed as a single layer. The electron injecting layer, thefirst electron transporting layer (ETL) 205 and the hole blocking layercan be referred to as an electron transmitting layer.

An electron is supplied from the second electrode 115 to the firstemitting material layer 203 a through the first electron transportinglayer (ETL) 205, and a hole is supplied from the first auxiliary layer208 to the first emitting material layer 203 a. The electron suppliedthrough the first electron transporting layer (ETL) 205 and the holesupplied from the first auxiliary layer 208 are recombined in the firstemitting material 203 a to generate a light.

The first auxiliary layer 208 can include a second hole transportinglayer (HTL2) (not shown) adjacent to the first emitting material layer203 a and a second electron transporting layer (ETL2) (not shown)adjacent to the second emitting material layer 203 b.

A hole injecting layer (HIL) (not shown) can be disposed between thesecond hole transporting layer and the second emitting material layer203 b, and an electron injecting layer (EIL) (not shown) can be disposedbetween the second electron transporting layer and the first emittingmaterial layer 203 a.

An electron blocking layer (EBL) (not shown) can be disposed between thefirst emitting material layer 203 a and the second hole transportinglayer. Since the electron blocking layer (EBL) prevents transmission ofan electron injected into the first emitting material layer 203 a to thesecond hole transporting layer, combination of a hole and an electron isimproved in the first emitting material layer 203 a and an emissionefficiency of the first emitting material layer 203 a is improved.

A hole blocking layer (HBL) (not shown) can be disposed between thesecond electron transporting layer and the second emitting materiallayer 203 b. Since the hole blocking layer prevents transmission of ahole injected into the second emitting material layer 203 b to thesecond electron transporting layer, combination of a hole and anelectron is improved in the second emitting material layer 203 b and anemission efficiency of the second emitting material layer 203 b isimproved.

The electron blocking layer (EBL) and the second hole transporting layercan be formed as a single layer, and the second electron transportinglayer and the hole blocking layer can be formed as a single layer. Thehole injecting layer, the second hole transporting layer and theelectron blocking layer (EBL) can be referred to as a hole transportinglayer, and the electron injecting layer, the second electrontransporting layer and the hole blocking layer can be referred to as anelectron transmitting layer.

A first charge generating layer (CGL1) can be disposed between thesecond hole transporting layer and the second electron transportinglayer of the first auxiliary layer 208. The first charge generatinglayer can adjust a charge balance between the first emitting materiallayer 203 a and the second emitting material layer 203 b. For example,the hole injecting layer can be disposed between the second holetransporting layer and the first charge generating layer, and theelectron injecting layer can be disposed between the first chargegenerating layer and the second electron transporting layer.

The first charge generating layer can include a positive type chargegenerating layer (P-CGL) and a negative type charge generating layer(N-CGL). The positive type charge generating layer can supply a hole tothe first emitting material layer 203 a, and the negative type chargegenerating layer can supply an electron to the second emitting materiallayer 203 b.

An electron is supplied from the first auxiliary layer 208 to the secondemitting material layer 203 b, and a hole is supplied from the secondauxiliary layer 209 to the second emitting material layer 203 b. Theelectron supplied from the first auxiliary layer 208 and the holesupplied from the second auxiliary layer 209 are recombined in thesecond emitting material 203 b to generate a light.

The second auxiliary layer 209 can include a third hole transportinglayer (HTL3) adjacent to the second emitting material layer 203 b and athird electron transporting layer (ETL3) adjacent to the third emittingmaterial layer 203 c.

A hole injecting layer (HIL) can be disposed between the third holetransporting layer (HTL3) and the third emitting material layer 203 c,and an electron injecting layer (EIL) can be disposed between the thirdelectron transporting layer and the second emitting material layer 203b.

An electron blocking layer (EBL) can be disposed between the secondemitting material layer 203 b and the third hole transporting layer(HTL3). Since the electron blocking layer (EBL) prevents transmission ofan electron injected into the third second emitting material layer 203 bto the third hole transporting layer (HTL3), combination of a hole andan electron is improved in the second emitting material layer 203 b andan emission efficiency of the second emitting material layer 203 b isimproved.

A hole blocking layer (HBL) can be disposed between the third electrontransporting layer and the third emitting material layer 203 c. Sincethe hole blocking layer prevents transmission of a hole injected intothe third emitting material layer 203 c to the third electrontransporting layer, combination of a hole and an electron is improved inthe third emitting material layer 203 c and an emission efficiency ofthe third emitting material layer 203 c is improved.

The electron blocking layer (EBL) and the third hole transporting layer(HTL3) can be formed as a single layer, and the third electrontransporting layer and the hole blocking layer can be formed as a singlelayer. The hole injecting layer, the third hole transporting layer(HTL3) and the electron blocking layer (EBL) can be referred to as ahole transporting layer, and the electron injecting layer, the thirdelectron transporting layer and the hole blocking layer can be referredto as an electron transmitting layer.

A second charge generating layer (CGL2) can be disposed between thethird hole transporting layer (HTL3) and the third electron transportinglayer of the second auxiliary layer 209. The second charge generatinglayer can adjust a charge balance between the second emitting materiallayer 203 b and the third emitting material layer 203 c. For example,the hole injecting layer can be disposed between the third holetransporting layer (HTL3) and the second charge generating layer, andthe electron injecting layer can be disposed between the second chargegenerating layer and the third electron transporting layer.

The second charge generating layer can include a positive type chargegenerating layer (P-CGL) and a negative type charge generating layer(N-CGL). The positive type charge generating layer can supply a hole tothe second emitting material layer 203 b, and the negative type chargegenerating layer can supply an electron to the third emitting materiallayer 203 c.

An electron is supplied from second auxiliary layer 209 to the thirdemitting material layer 203 c, and a hole is supplied from the firstelectrode 111 to the third emitting material layer 203 c through thefirst hole transporting layer (HTL1) 207. The electron supplied from thesecond auxiliary layer 209 and the hole supplied through the first holetransporting layer (HTL1) 207 are recombined in the third emittingmaterial 203 c to generate a light.

In the light emitting layer 113 of the OLED display device 100 accordingto the second embodiment of the present disclosure, each of the firstand second emitting material layers adjacent to the second electrode 115emits one of a blue colored light and a sky-blue colored light having awavelength of 440 nm to 480 nm, and the third emitting material layer203 c adjacent to the first electrode 111 emits a yellow-green coloredlight having a wavelength of 510 nm to 590 nm. As a result, the lightemitting diode E emits a white light by mixing the blue colored lightand the yellow-green colored light from the first, second and thirdemitting material layers 203 a, 203 b and 204 c.

The first and second emitting material layers 203 a and 203 b emittingthe blue colored light have a relatively low emission efficiency ascompared with the third emitting material layer 203 c emitting theyellow-green colored light. Since two of the first and second emittingmaterial layers 203 a and 203 b emit the blue colored light and one ofthe third emitting material layer 203 c emits the yellow-green coloredlight, a luminance of the blue colored light of a relatively lowemission efficiency increases and a uniform white light is obtained.

In the a light emitting diode E of the organic light emitting diode(OLED) display device 100 according to the second embodiment of thepresent disclosure, the first, second and third emitting material layers203 a, 203 b and 203 c emitting blue, blue and yellow-green coloredlights, respectively, are sequentially disposed under the secondelectrode 115.

Each of the first, second and third emitting material layers 203 a, 203b and 203 c can include at least one host and at least one dopant or amixed host where at least two hosts are mixed and at least one dopant.When the mixed host includes a host having a hole transporting propertyand a host having an electron transporting property, a charge balance ofeach of the first, second and third emitting material layers 203 a, 203b and 203 c can be adjusted and an efficiency of each of the first,second and third emitting material layers 203 a, 203 b and 203 c can beimproved. The dopant can include a fluorescent dopant or aphosphorescent dopant.

Here, the first, second and third emitting material layers 203 a, 203 band 203 c emitting blue, blue and yellow-green colored lights,respectively, are disposed at positions having a maximum emissionefficiency in an effective emission region B (of FIG. 2) of the lightemitting layer 113 constituting a microlens ML (of FIG. 2).

In FIG. 5, the blue colored light of the light emitting layer 113constituting the microlens ML with the first and second electrodes 111and 115 has additional fifth, sixth and seventh blue cavity peaks B5, B6and B7 between the first and second blue cavity peaks B1 and B2 (of FIG.3).

The x-axis represents a distance from the second electrode 115 and they-axis represents an external quantum efficiency (EQE). The EQE is anexternal light efficiency which is an emission efficiency when a lightis emitted from the first and second emitting material layers 203 a and203 b to an exterior. Relative maximum values of the EQE correspond tothe cavity peaks.

A curve C represents an experimental result obtained by measuring theEQE of the emitting material layer emitting the blue colored light withrespect to the distance from the second electrode in the OLED displaydevice according to the comparison example where the first electrode,the light emitting layer and the second electrode have a flat shape. Acurve D represents an experimental result obtained by measuring the EQEof the emitting material layer 203 a and 203 b emitting the blue coloredlight with respect to the distance from the second electrode 115 in theOLED display device 100 according to the second embodiment of thepresent disclosure.

The curve C has the first and second blue cavity peaks B1 and B2 havinga relatively strong EQE at the distance of 250 Å and 1500 Å,respectively, from the second electrode. The curve D has the fifth,sixth and seventh blue cavity peaks B5, B6 and B7 as well as the firstand second blue cavity peaks B1 and B2 The fifth blue cavity peak B5 cancorrespond to the distance of a range of 350 Å to 460 Å from the secondelectrode 115, the sixth blue cavity peak B6 can correspond to thedistance of a range of 1000 to 1300 Å from the second electrode 115, andthe seventh blue cavity peak B7 can correspond to the distance of arange of 1700 Å to 2300 Å from the second electrode 115.

In the OLED display device 100 where the first electrode 111, the lightemitting layer 113 and the second electrode 115 constitute the microlensML for increasing the EQE, the additional fifth, sixth and seventh bluecavity peaks B5, B6 and B7 can be generated due to partial distortion ofthe distance and the position of the emitting material layer 203 a and203 b for the blue cavity peak by the microlens ML.

As a result, the first, second and third emitting material layers 203 a,203 b and 203 c can satisfy the cavity peaks by disposing the secondemitting material layer 203 b emitting the blue colored light tocorrespond to one of the fifth, sixth and seventh blue cavity peaks B5,B6 and B7 added by the microlens ML. As a result, the maximum emissionefficiency is obtained in the OLED display device 100 according to thesecond embodiment of the present disclosure.

In the light emitting diode E according to the second embodiment, thefirst emitting material layer 203 a emitting the blue colored light canbe disposed between the second electrode 115 and the second emittingmaterial layer 203 a emitting the blue colored light to correspond toone of the first and fifth blue cavity peaks B1 and B5.

For example, the first emitting material layer 203 a can be separatedfrom a bottom surface of the second electrode 115 of a cathode by afirst distance L1 within a range of 290 Å to 460 Å.

The second emitting material layer 203 b emitting the blue colored lightcan be disposed between the first emitting material layer 203 a emittingthe blue colored light and the third emitting material layer 203 cemitting the yellow-green colored light to correspond to one of sixthand seventh blue cavity peaks B6 and B7.

For example, the second emitting material layer 203 b can be separatedfrom a bottom surface of the second electrode 115 of a cathode by asecond distance L2 within a range of 1060 Å to 1260 Å or within a rangeof 1860 Å to 2260 Å.

The third emitting material layer 203 c emitting the yellow-greencolored light can be disposed adjacent to the first electrode 111 ascompared with the first and second emitting material layers 203 a and203 b emitting the blue colored light to correspond to the secondyellow-green cavity peaks YG2 (of FIG. 3).

For example, the third emitting material layer 203 c can be separatedfrom a bottom surface of the second electrode 115 of a cathode by athird distance L3 within a range of 2500 Å to 2700 Å.

In the OLED display device 100 according to the second embodiment of thepresent disclosure, the first emitting material layer 203 a emitting theblue colored light can be disposed to correspond to one of the first andfifth blue cavity peaks B1 and B5. The second emitting material layer203 b emitting the blue colored light can be disposed to correspond toone of the sixth and seventh blue cavity peaks B6 and B7. The thirdemitting material layer 203 c emitting the yellow-green colored lightcan be disposed to correspond to the second yellow-green cavity peakYG2.

Since the first, second and third emitting material layers 203 a, 203 band 203 c are disposed to correspond to the cavity peaks, the maximumemission efficiency can obtained in the OLED display device 100 wherethe first electrode 111, the light emitting layer 113 and the secondelectrode 115 constituting the microlens ML.

Specifically, the first emitting material layer 203 a can be disposed ata position of the first distance L1 within a range of 290 Å to 460 Å,the second emitting material layer 203 b can be disposed at a positionof the second distance L2 within a range of 1060 Å to 1260 Å or within arange of 1860 Å to 2260 Å, and the third emitting material layer 203 ccan be disposed at a position of the third distance L3 within a range of2500 Å to 2700 Å. As a result, the maximum emission efficiency isobtained, and a total thickness of the light emitting layer 113 isreduced at the same time. For example, the light emitting layer 113 canhave the total thickness smaller than 4000 Å, e.g., the thickness withina range of 3600 Å to 4000 Å.

In the OLED display device 100 according to the second embodiment of thepresent disclosure, since the first electrode 111, the light emittinglayer 113 and the second electrode 115 constitute the microlens ML, thelight extraction efficiency increases. In addition, since the first,second and third emitting material layers 203 a, 203 b and 203 c aredisposed to correspond to the cavity peaks based on the effectiveemission region B of the light emitting layer 113 constituting themicrolens ML, each of the first, second and third emitting materiallayers 203 a, 203 b and 203 c has the maximum emission efficiency andthe emission efficiency of the OLED display device 100 furtherincreases.

Further, the total thickness of the light emitting layer 113 of the OLEDdisplay device 100 is reduced with increase of the light extractionefficiency and the emission efficiency.

When the thickness of the light emitting layer 113 increases, theemission efficiency of the light emitting diode E is reduced due toabsorption of the light from the first, second and third emittingmaterial layers 203 a, 203 b and 203 c by the organic layer, or theprocess efficiency is reduced such that the fabrication time for thelight emitting layer 113 increases. In the OLED display device 100according to the second embodiment of the present disclosure, since thefourth thickness LA of the light emitting layer 113 is reduced, thereduction in emission efficiency and process efficiency is prevented.

In addition, since the distances from the second electrode 115 to theemitting material layers 203 a, 203 b and 203 c in the concave portions118 (of FIG. 2) of the light emitting layer 113 constituting themicrolens ML are determined different from the distances from the secondelectrode 115 to the emitting material layers 203 a, 203 b and 203 c inthe effective emission region B of the side surface portion 117 c (ofFIG. 2) of the convex portions 117 (of FIG. 2), the emitting materiallayers 203 a, 203 b and 203 c are disposed to satisfy the cavity peaksof the optical property based on the effective emission region B (ofFIG. 2) of the light emitting layer 113. As a result, the lightextraction efficiency of the OLED display device 100 increases.

Further, since the total thickness of the light emitting layer 113and/or the light emitting diode E is reduced, the reduction in emissionefficiency and process efficiency is prevented.

The present disclosure also relates to and is not limited to thefollowing aspects.

In the present disclosure, an organic light emitting diode displaydevice includes: an overcoating layer on a substrate having an emittingarea and a non-emitting area and including a plurality of convexportions and a plurality of concave portions; a first electrode on theovercoating layer; a light emitting layer on the first electrode; and asecond electrode on the light emitting layer, wherein the light emittinglayer includes first, second and third emitting material layerssequentially under the second electrode, and wherein the first emittingmaterial layer emits a first light of a first wavelength, the secondemitting material layer emits the first light of the first wavelength,and the third emitting material layer emits a second light of a secondwavelength different from the first wavelength.

In the present disclosure, the first wavelength is within a range of 440nm to 480 nm, and the second wavelength is within a range of 510 nm to590 nm.

In the present disclosure, the first emitting material layer is disposedto have a distance of 290 Å to 460 Å from a bottom surface of the secondelectrode.

In the present disclosure, the second emitting material layer isdisposed to have a distance of 1060 Å to 1260 Å from a bottom surface ofthe second electrode.

In the present disclosure, the second emitting material layer isdisposed to have a distance of 1860 Å to 2260 Å from a bottom surface ofthe second electrode.

In the present disclosure, the third emitting material layer is disposedto have a distance of 2500 Å to 2700 Å from a bottom surface of thesecond electrode.

In the present disclosure, the light emitting layer has a thicknesswithin a range of 3600 Å to 4000 Å.

In the present disclosure, a thickness of the light emitting layercorresponding to the plurality of convex portions is smaller than athickness of the light emitting layer corresponding to the plurality ofconcave portions.

In the present disclosure, the first light includes one of a bluecolored light and a sky-blue colored light, and the second lightincludes a yellow-green light.

In the present disclosure, a thickness of at least one of the firstelectrode and the second electrode corresponding to the plurality ofconvex portions is smaller than a thickness of the at least one of thefirst electrode and the second electrode corresponding to the pluralityof concave portions.

In the present disclosure, each convex portion has a cross-section of atriangle shape including a vertex, a bottom side and a hypotenuse.

In the present disclosure, an angle of the hypotenuse of each convexportion gradually increase from a bottom side to the vertex.

In the present disclosure, the organic light emitting diode displaydevice further includes a wavelength converting layer interposed betweenthe substrate and the overcoating layer, and an edge portion of thewavelength converting layer extends beyond an edge portion of theplurality of convex portions and the plurality of concave portionstoward the non-emitting area

In the present disclosure, the organic light emitting diode displaydevice further includes a bank on the overcoating layer, and includingan opening exposing the first electrode, and the plurality of convexportions and the plurality of concave portions are formed in theopening.

In the present disclosure, the plurality of convex portions and theplurality of concave portions contact an edge portion of the bank, andthe bank overlays an edge portion of the plurality of convex portionsand the plurality of concave portions

In the present disclosure, an edge portion of the wavelength convertinglayer, an edge portion of the plurality of convex portions and theplurality of concave portions and an edge portion of the bank overlapone another in the non-emitting area.

In the present disclosure, a border portion of the emitting area and thenon-emitting area overlaps an edge portion of the plurality of convexportions and the plurality of concave portions.

In the present disclosure, an organic light emitting diode displaydevice includes: an overcoating layer on a substrate and including aplurality of convex portions and a plurality of concave portions thatare integrally formed in the overcoating layer; and a light emittinglayer on the overcoating layer and including first, second and thirdemitting material layers, wherein the first emitting material layeremits a first light of a first wavelength, the second emitting materiallayer emits the first light of the first wavelength, and the thirdemitting material layer emits a second light of a second wavelengthdifferent from the first wavelength, and wherein the first, second andthird lights confined in an interior of the light emitting layer due toa total reflection is transmitted with an angle smaller than a criticalangle of the total reflection by the overcoating layer to be extractedto an exterior by a multiple reflection.

In the present disclosure, the organic light emitting diode displaydevice further includes: a first electrode on the overcoating layer; anda second electrode on the light emitting layer, and the first, secondand third emitting material layers are sequentially stacked under thesecond electrode.

In the present disclosure, the first wavelength is within a range of 440nm to 480 nm, and the second wavelength is within a range of 510 nm to590 nm.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An organic light emitting diode display device,comprising: an overcoating layer on a substrate having an emitting areaand a non-emitting area and including a plurality of convex portions anda plurality of concave portions; a first electrode on the overcoatinglayer; a light emitting layer on the first electrode; and a secondelectrode on the light emitting layer, wherein the light emitting layerincludes first, second and third emitting material layers sequentiallyunder the second electrode, wherein the first emitting material layeremits a first light of a first wavelength, the second emitting materiallayer emits the first light of the first wavelength, and the thirdemitting material layer emits a second light of a second wavelengthdifferent from the first wavelength, wherein the first light includesone of a blue colored light and a sky-blue colored light, wherein thesecond emitting material layer emitting the first light of the firstwavelength is disposed to have a distance within one of a range of 1060Å to 1260 Å and a range of 1860 Å to 2260 Å from a bottom surface of thesecond electrode, and wherein a thickness of at least one of the firstelectrode and the second electrode corresponding to the plurality ofconvex portions is smaller than a thickness of the at least one of thefirst electrode and the second electrode corresponding to the pluralityof concave portions.
 2. The organic light emitting diode display deviceof claim 1, wherein the first wavelength is within a range of 440 nm to480 nm, and the second wavelength is within a range of 510 nm to 590 nm.3. The organic light emitting diode display device of claim 1, whereinthe first emitting material layer is disposed to have a distance withina range of 290 Å to 460 Å from the bottom surface of the secondelectrode.
 4. The organic light emitting diode display device of claim1, wherein the third emitting material layer is disposed to have adistance within a range of 2500 Å to 2700 Å from the bottom surface ofthe second electrode.
 5. The organic light emitting diode display deviceof claim 1, wherein the light emitting layer has a thickness within arange of 3600 Å to 4000 Å.
 6. The organic light emitting diode displaydevice of claim 1, wherein a thickness of the light emitting layercorresponding to the plurality of convex portions is smaller than athickness of the light emitting layer corresponding to the plurality ofconcave portions.
 7. The organic light emitting diode display device ofclaim 1, wherein the second light includes a yellow-green light.
 8. Theorganic light emitting diode display device of claim 1, wherein eachconvex portion has a cross-section of a triangle shape including avertex, a bottom side and a hypotenuse.
 9. The organic light emittingdiode display device of claim 8, wherein an angle of the hypotenuse ofeach convex portion gradually increase from the bottom side to thevertex.
 10. The organic light emitting diode display device of claim 1,further comprising a wavelength converting layer interposed between thesubstrate and the overcoating layer, wherein an edge portion of thewavelength converting layer extends beyond an edge portion of theplurality of convex portions and the plurality of concave portionstoward the non-emitting area.
 11. The organic light emitting diodedisplay device of claim 10, further comprising a bank on the overcoatinglayer, and including an opening exposing the first electrode, whereinthe plurality of convex portions and the plurality of concave portionsare formed in the opening.
 12. The organic light emitting diode displaydevice of claim 11, wherein the plurality of convex portions and theplurality of concave portions contact an edge portion of the bank, andwherein the bank overlays an edge portion of the plurality of convexportions and the plurality of concave portions.
 13. The organic lightemitting diode display device of claim 11, wherein an edge portion ofthe wavelength converting layer, an edge portion of the plurality ofconvex portions and the plurality of concave portions and an edgeportion of the bank overlap one another in the non-emitting area. 14.The organic light emitting diode display device of claim 1, wherein aborder portion of the emitting area and the non-emitting area overlapsan edge portion of the plurality of convex portions and the plurality ofconcave portions.
 15. An organic light emitting diode display device,comprising: an overcoating layer on a substrate and including aplurality of convex portions and a plurality of concave portions thatare integrally formed in the overcoating layer; and a light emittinglayer on the overcoating layer and including first, second and thirdemitting material layers, wherein the first emitting material layeremits a first light of a first wavelength, the second emitting materiallayer emits the first light of the first wavelength, and the thirdemitting material layer emits a second light of a second wavelengthdifferent from the first wavelength, wherein the first and second lightsconfined in an interior of the light emitting layer due to a totalreflection is transmitted with an angle smaller than a critical angle ofthe total reflection by the overcoating layer to be extracted to anexterior by a multiple reflection, wherein the first light includes oneof a blue colored light and a sky-blue colored light, wherein the secondemitting material layer emitting the first light of the first wavelengthis disposed to have a distance within one of a range of 1060 Å to 1260 Åand a range of 1860 Å to 2260 Å from a bottom surface of the secondelectrode, and wherein a thickness of at least one of a first electrodeand a second electrode corresponding to the plurality of convex portionsis smaller than a thickness of the at least one of the first electrodeand the second electrode corresponding to the plurality of concaveportions.
 16. The organic light emitting diode display device of claim15, further comprising: the first electrode on the overcoating layer;and the second electrode on the light emitting layer, wherein the first,second and third emitting material layers are sequentially stacked underthe second electrode.
 17. The organic light emitting diode displaydevice of claim 15, wherein the first wavelength is within a range of440 nm to 480 nm, and the second wavelength is within a range of 510 nmto 590 nm.
 18. The organic light emitting diode display device of claim1, further comprising: a wavelength converting layer interposed betweenthe substrate and the overcoating layer; and a bank on the overcoatinglayer, the bank including an opening exposing the first electrode,wherein an edge portion of the wavelength converting layer extendsbeyond an edge portion of the bank such that the edge portion of thewavelength converting layer and the edge portion of the bank overlapeach other.